[PATCH 07/13] KVM: SVM: Add VNMI support in get/set_nmi_mask

[Maxim Levitsky <mlevitsk@xxxxxxxxxx>]

From: Santosh Shukla <santosh.shukla@xxxxxxx>

VMCB intr_ctrl bit12 (V_NMI_MASK) is set by the processor when handling
NMI in guest and is cleared after the NMI is handled. Treat V_NMI_MASK
as read-only in the hypervisor except for the SMM case where hypervisor
before entring and after leaving SMM mode requires to set and unset
V_NMI_MASK.

Adding API(get_vnmi_vmcb) in order to return the correct vmcb for L1 or
L2.

Maxim:
   - made set_vnmi_mask/clear_vnmi_mask/is_vnmi_mask warn if called
     without vNMI enabled
   - clear IRET intercept in svm_set_nmi_mask even with vNMI

Signed-off-by: Santosh Shukla <santosh.shukla@xxxxxxx>
Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
---
 arch/x86/kvm/svm/svm.c | 18 ++++++++++++++-
 arch/x86/kvm/svm/svm.h | 52 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 08a7b2a0a29f3a..c16f68f6c4f7d7 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3618,13 +3618,29 @@ static int svm_nmi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 
 static bool svm_get_nmi_mask(struct kvm_vcpu *vcpu)
 {
-	return !!(vcpu->arch.hflags & HF_NMI_MASK);
+	struct vcpu_svm *svm = to_svm(vcpu);
+
+	if (is_vnmi_enabled(svm))
+		return is_vnmi_mask_set(svm);
+	else
+		return !!(vcpu->arch.hflags & HF_NMI_MASK);
 }
 
 static void svm_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 
+	if (is_vnmi_enabled(svm)) {
+		if (masked)
+			set_vnmi_mask(svm);
+		else {
+			clear_vnmi_mask(svm);
+			if (!sev_es_guest(vcpu->kvm))
+				svm_clr_intercept(svm, INTERCEPT_IRET);
+		}
+		return;
+	}
+
 	if (masked) {
 		vcpu->arch.hflags |= HF_NMI_MASK;
 		if (!sev_es_guest(vcpu->kvm))
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index f5383104d00580..bf7f4851dee204 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -35,6 +35,7 @@ extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
 extern bool npt_enabled;
 extern int vgif;
 extern bool intercept_smi;
+extern bool vnmi;
 
 enum avic_modes {
 	AVIC_MODE_NONE = 0,
@@ -531,6 +532,57 @@ static inline bool is_x2apic_msrpm_offset(u32 offset)
 	       (msr < (APIC_BASE_MSR + 0x100));
 }
 
+static inline struct vmcb *get_vnmi_vmcb(struct vcpu_svm *svm)
+{
+	if (!vnmi)
+		return NULL;
+
+	if (is_guest_mode(&svm->vcpu))
+		return svm->nested.vmcb02.ptr;
+	else
+		return svm->vmcb01.ptr;
+}
+
+static inline bool is_vnmi_enabled(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (vmcb)
+		return !!(vmcb->control.int_ctl & V_NMI_ENABLE);
+	else
+		return false;
+}
+
+static inline bool is_vnmi_mask_set(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (!WARN_ON_ONCE(!vmcb))
+		return false;
+
+	return !!(vmcb->control.int_ctl & V_NMI_MASK);
+}
+
+static inline void set_vnmi_mask(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (!WARN_ON_ONCE(!vmcb))
+		return;
+
+	vmcb->control.int_ctl |= V_NMI_MASK;
+}
+
+static inline void clear_vnmi_mask(struct vcpu_svm *svm)
+{
+	struct vmcb *vmcb = get_vnmi_vmcb(svm);
+
+	if (!WARN_ON_ONCE(!vmcb))
+		return;
+
+	vmcb->control.int_ctl &= ~V_NMI_MASK;
+}
+
 /* svm.c */
 #define MSR_INVALID				0xffffffffU
 
-- 
2.34.3